调整键盘出现/消失的视图：动画曲线问题

Posted 2023-02-24

【中文标题】调整键盘出现/消失的视图：动画曲线问题

【英文标题】：Adjusting a view for keyboard appearing/disappearing: problem with animation curve

【发布时间】：2020-04-04 01:32:32

【问题描述】：

我正在尝试创建一个 SwiftUI 视图修改器，它添加底部填充以响应屏幕键盘的出现或消失。这是我正在使用的方法：

struct KeyboardAdjustingModifier: ViewModifier 
    @ObservedObject private var responder = KeyboardResponder()

    func body(content: Content) -> some View 
        GeometryReader  proxy in
            content
                .padding(.bottom, self.bottomPadding(in: proxy))
        
    

    func bottomPadding(in proxy: GeometryProxy) -> CGFloat 
        if responder.endFrame == .zero 
            return 0
         else 
            return max(0, proxy.frame(in: .global).maxY - self.responder.endFrame.minY)
        
    


fileprivate final class KeyboardResponder: ObservableObject 
    @Published var endFrame: CGRect = .zero

    init(notificationCenter: NotificationCenter = .default) 
        notificationCenter.addObserver(self,
                                       selector: #selector(keyboardWillShowOrChangeFrame(notification:)),
                                       name: UIResponder.keyboardWillShowNotification, object: nil)
        notificationCenter.addObserver(self,
                                       selector: #selector(keyboardWillShowOrChangeFrame(notification:)),
                                       name: UIResponder.keyboardWillChangeFrameNotification, object: nil)
        notificationCenter.addObserver(self,
                                       selector: #selector(keyboardWillHide(notification:)),
                                       name: UIResponder.keyboardWillHideNotification, object: nil)
    

    @objc private func keyboardWillShowOrChangeFrame(notification: Notification) 
        withAnimation(Animation(curve: notification.animationCurve, duration: notification.duration)) 
            endFrame = notification.endFrame
        
    

    @objc private func keyboardWillHide(notification: Notification) 
        withAnimation(Animation(curve: notification.animationCurve, duration: notification.duration)) 
            endFrame = .zero
        
    

    struct Info 
        let curve: UIView.AnimationCurve
        let duration: TimeInterval
        let endFrame: CGRect
    


fileprivate extension Animation 
    init(curve: UIView.AnimationCurve, duration: TimeInterval) 
        switch curve 
        case .easeInOut:
            self = .easeInOut(duration: duration)
        case .easeIn:
            self = .easeIn(duration: duration)
        case .easeOut:
            self = .easeOut(duration: duration)
        case .linear:
            self = .linear(duration: duration)
        @unknown default:
            self = .easeInOut(duration: duration)
        
    


fileprivate extension Notification 
    var animationCurve: UIView.AnimationCurve 
        guard let rawValue = (userInfo?[UIResponder.keyboardAnimationCurveUserInfoKey] as? Int) else 
            return UIView.AnimationCurve.linear
        

        return UIView.AnimationCurve(rawValue: rawValue)!
    

    var duration: TimeInterval 
        userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? TimeInterval ?? 0
    

    var endFrame: CGRect 
        userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect ?? .zero
    

我遇到的问题是 SwiftUI 动画曲线似乎与键盘的动画曲线完全不同：

有谁知道是否可以像这样将 SwiftUI 动画与 UIKit 同步？我将通知的 userInfo 中的动画曲线信息映射到 SwiftUI 动画曲线的方式很可能存在错误。还是我应该考虑另一种解决这个问题的方法？

我尝试的另一件事是使用UIHostingController 直接在 UIKit 中处理动画。它与键盘正确同步，但如果 SwiftUI 也在同时为内容制作动画，我在我的动画块中调用 layoutIfNeeded 时遇到了崩溃。

【参考方案1】：

这是我正在使用的，它几乎可以完美运行：

演示

代码

public extension View 
    func adaptToKeyboard() -> some View 
        modifier(AdaptToSoftwareKeyboard())
    


public struct AdaptToSoftwareKeyboard: ViewModifier 
    @State var currentHeight: CGFloat = 0

    public func body(content: Content) -> some View 
        content
            .padding(.bottom, currentHeight)
            .edgesIgnoringSafeArea(.bottom)
            .animation(.spring())
            .onAppear(perform: subscribeToKeyboardEvents)
    

    private func subscribeToKeyboardEvents() 
        NotificationCenter.Publisher(
            center: NotificationCenter.default,
            name: UIResponder.keyboardWillShowNotification
        )
            .compactMap  $0.userInfo?["UIKeyboardFrameEndUserInfoKey"] as? CGRect 
            .map  $0.height 
            .subscribe(Subscribers.Assign(object: self, keyPath: \.currentHeight))

        NotificationCenter.Publisher(
            center: NotificationCenter.default,
            name: UIResponder.keyboardWillHideNotification
        )
            .compactMap  _ in CGFloat.zero 
            .subscribe(Subscribers.Assign(object: self, keyPath: \.currentHeight))
    

用法

someView()
    .adaptToKeyboard()

在此处使用演示进行测试：https://github.com/youjinp/SwiftUIKit